1. Field of the Invention
This invention relates to dental bleaches and, more particularly, to a novel dental bleach and method for use by a dental professional to remove stains from teeth whereby the dental professional is provided with a container of fumed silica and a container of hydrogen peroxide that can be mixed directly into the fumed silica to form a paste that is easier to use and safer to handle.
2. The Prior Art
Discolorations of the dentitation are traditionally classified into two main categories, extrinsic and intrinsic. Extrinsic stains result from the deposition of a film, pigment or calculus on the teeth. The familiar extrinsic discolorations generally result from the superficial staining of tooth surfaces. Coffee, tea, artificial food colorations, grapes, berries, and the smoking or chewing of tobacco are the usual causatives. The intensity of these stains may be worsened if there are enamel defects such as pits, cracks, grooves, when the dentin is exposed, or when recession has bared the root surface. These irregularities allow the stain to penetrate the tooth to a depth that makes removal of the stain extremely difficult or virtually impossible.
Intrinsic discolorations result from several causes which have either an endogenous or exogenous origin and which may occur during or after odontogenesis. During odontogenesis teeth may become discolored from changes in the quality or quantity of enamel or dentine, or from incorporation of discoloring agents into the hard tissues. Post-eruption discolorations occur when discoloring agents enter the dental hard tissues and may originate from the pulp cavity or tooth surface.
Intrinsic discolorations that occur during odontogenesis may result from a number of causes including inherited metabolic disorders such as ochronosis, also known as alkaptonuria or phenylketonuria, which is characterized by incomplete oxidation of tyrosine and phenylanine causing a buildup of homogenestic acid. This buildup may result in a dark brown discoloration of the permanent teeth.
Porphyria is a rare disorder of porphyrin metabolism and is usually congenital but can be acquired later in life. The hematoporphyrin pigment caused a characteristic reddish-brown discoloration of the teeth, called "erythrodontia" and is dispersed throughout the enamel, dentine and cementum.
Dental fluorosis is an enamel hypoplasia resulting from excessive ingestion of fluoride during the critical stages of dental development. The degree of fluorosis is directly proportional to the amount of fluoride absorbed. A brown stain of extrinsic origin is acquired of few years after the affected tooth as erupted into the oral cavity.
Tetracycline affects both the permanent teeth as well as the deciduous teeth because of its ability to cross the placental barrier. During mineralization tetracycline binds to the calcium to form a calcium-phosphate-tetracycline complex. The severity of the discoloration is related to the dose, duration, timing, and type of drug administered.
Intrinsic discoloration after odontogenesis results from several causes including trauma, aging, metals, dental materials, or foods and beverages. Trauma can cause hemorrhage in the dental pulp which ma result in the diffusion of blood pigments into the dental tubules. Aging, secondary and tertiary (atypical) dentine formation and pulp stones can also cause the tooth to appear a yellowish-brown color.
By direct contact and oxidation or by precipitation from the blood stream or saliva, metals may deposit in the dentine, cementum or enamel. The most common cause of metallic staining is corrosion products from amalgam restorations. Dental materials containing therapeutic agents such as polyantibiotic pastes, oil of cloves, creosote and the like can also discolor the dentition.
One of the commonly practiced techniques for removing discolorations, both extrinsic and intrinsic, is the practice of external bleaching. Hydrogen peroxide has been known for years as a dental bleaching agent although its cleansing action affects discoloring agents located within five to seven microns from the enamel surface. This is explained by the high inorganic content and limited permeability of the enamel. One report suggests that the improvement of esthetics in cases of tetracycline and similar type stainings using hydrogen peroxide is attributed more to the alteration of the light refraction of the surface enamel than to the removal of the discoloring agents and continues on to suggest that the results are only temporary.
Several techniques exist for the application of hydrogen peroxide as a bleaching agent. The major point of difference in these techniques are the temperature to which the tooth is heated and the duration of that heating so that there appears to be no apparent consensus established for the time and temperature. Apparently, the pain threshold of the patient to the treatment is the guideline so that these parameters will be established by the patient reaction which can be altered by the psychological state of the patient.
The basic prior art technique for bleaching a tooth is to carefully shield the patient's surrounding gum tissue using a tight fitting rubber dam along with petrolatum or cocoa butter between the dam and the soft tissue. The tooth surface is then treated with a flour of pumice and etched with thirty-seven percent phosphoric acid for one minute after which it is washed and dried. The enamel surfaces are then treated by applying cotton gauze or the equivalent saturated with thirty percent hydrogen peroxide and a low heat treatment is applied. One technique for heating is through an exothermic chemical reaction caused by mixing calcium carbonate with the hydrogen peroxide. Other heat sources can also be used, such as a heating lamp or a heated metal instrument applied to the tooth. The tooth is then washed thoroughly, dried and sealed with a sealing agent. At all times, great care is taken to protect both the patient and the dental team from the liquid hydrogen peroxide.
A number of publications discuss various aspects of the foregoing, including by way of example:
"Bleaching," by Ronald A. Feinman, DMD, CDA Journal, April 1987, pages 10-13.
"Chemical agents for removing intrinsic stains from vital teeth. I. Technique development," by Susan A. McEvoy, DMD, MS, Quintessence International, Vol. 20, No. 5, 1989, pages 323-328.
"Chemical agents for removing intrinsic stains from vital teeth. II. Current techniques and their clinical application," by Susan A. McEvoy, DMD, MS, Quintessence International, Vol. 20, No. 6, 1989, pages 379-384.
"Bleaching Stains Related to Trauma or Periapical Inflammation," by Susan A. McEvoy, DMD, MS, The Compendium of Continuing Education, Vol. VII, No. 6, June 1986, pages 420-428.
"Bleaching Vital Teeth: A Review and Clinical Study," by Dan Nathanson, DMD, MSD and Cesar Parra, DDS, Compend Contin Educ Dent., Vol. VIII, No. 7 pages 490-497.
"Anterior composite resins and veneers: treatment planning, preparation, and finishing," by Alan R. Weinstein, DDS, JADA (Special Issue), September 1988, pages 38E-45E.
"Bleaching teeth: new materials-new role," by Ronald E. Goldstein, DDS, JADA (Special Issue), December, 1987, pages 44E-52E.
"An In Vitro Comparison of Different Bleaching Agents in the Discolored Tooth," by Stewart Ho, DMD and Albert C. Goerig, DDS, MS, FICD, Journal of Endodontics, Vol. 15, No. 3, March 1989, pages 106-111.
"Bleaching Procedures for Teeth with Vital and Nonvital Pulps," by Richard E. Walton, Current Treatment in Dental Practice, N. Levine (ed.), Philadelphia: W. B. Saunders, 1986, page 202.
"A method for bleaching discolored vital teeth," by Edward J. Swift, Jr., DMD, Quintessence International, Vol. 19, No. 9, 1988, pages 607-612.
"The Role of Bleaching in Esthetics," by Donald Arens, DDS, MSD, Dental Clinics of North America, Vol. 33, No.2, April 1989, pages 319-336.
"The Etiology and Treatment of Intrinsic Discolourations," by P. A. Hayes, DMD, C. Full, B.S., DDS, MS and J. Pinkham, BS, DDS, MS, J. Canadian Dental Assoc., Vol. 52, No. 3, March 1986, pages 217-220.
Hydrogen peroxide has long been recognized for its effectiveness in curative and/or prophylactic treatments with respect to caries, dental plaque, gingivitis, periodontia, mouth odor, tooth stains, recurrent aphthous ulcers, denture irritations, orthodontic appliance lesions, post extraction and postperiodontal surgery, traumatic oral lesions and mucosal infections, herpetic stomatitis, and the like. Peroxide-containing agents in the oral cavity exert a chemomethanical action generating thousands of tiny oxygen bubbles produced by interaction with tissue and salivary enzymes.
However, it is well known that hydrogen peroxide in oral compositions is unstable in storage due to its incompatibility with and/or interaction with other common ingredients in the composition. Numerous attempts have been made to overcome this problem and to thereby provide a suitable dental product having hydrogen peroxide as an active ingredient without its having lost its inherent, oxygen-producing capability.
Sompayrac (U.S. Pat. No. 4,226,851) discloses a stable dental hygiene composition including hydrogen peroxide and zinc chloride in the presence of a water-soluble vitamin E. The presence of the water-soluble vitamin E acts to prevent the usual instability of hydrogen peroxide in a solution containing a metal salt while still allowing a desirable release of oxygen from the hydrogen peroxide when the mixture is used, that is, in the presence of organic matter.
Schaeffer (U.S. Pat. Nos. 4,687,663 and 4,849,213) discloses a dual-component system for delivering a first semi-solid component having hydrogen peroxide as an active ingredient and a second semi-solid component having sodium bicarbonate.
Ng, et al. (U.S. Pat. Nos. 4,788,052; 4,839,156; and 4,839,157) disclose stable hydrogen peroxide dental gel compositions including one having a combination of hydrophilic and hydrophobic fumed silicas along with a polyethylene glycol humectant, flavor, sweetening agent, sodium benzoate, and a nonionic surfactant as the essential ingredients. The order of addition of the essential ingredients is carefully controlled to protect the stability of the hydrogen peroxide.
From the foregoing, it is clear that numerous attempts have been made to safely utilize the therapeutic and bleaching capabilities of hydrogen peroxide As a liquid it can splash or otherwise be distributed as droplets which contact and damage other surfaces or tissue. Placed in a gel or semi-solid medium, the hydrogen peroxide reacts with most compounds to prematurely decompose and release its oxygen component thereby becoming water.
In view of the present state of the art it would be a significant advancement in the art to provide the dental professional with a high concentration of hydrogen peroxide in a safe, effective, and easily controllable vehicle for delivering the hydrogen peroxide to the dental surface being treated by the dental professional. It would also be an advancement in the art if the dental professional could have available hydrogen peroxide in an easily handled paste which would control the hydrogen peroxide and at the same time act as a polishing agent for polishing the dental surface. Such a novel invention is disclosed and claimed herein.